Expanding your storage space with an external hard drive is a simple matter of plugging in via USB or FireWire. But buying an internal hard drive for your laptop or notebook offers a number of convenient benefits. Most notebook hard drive are easy to install—the only challenge is choosing a hard disk drive that is compatible with your particular laptop and will deliver the performance and reliability that you need. Follow the guidelines below when shopping for a notebook hard drive.

Physical Dimensions

Refer to your notebook's manual to determine which size hard drive you need. Most full-size and mid-size laptops take a 2.5-inch hard drive, while subnotebooks, ultraportables and netbooks take a 1.8-inch hard drive. 3.5-inch hard drives are reserved for desktop computers.

You should also pay close attention to the thickness of a hard drive. This is an often overlooked detail. For example, a 12.5 mm thick hard drive won't fit into a laptop that only accommodates hard drives up to 9.5 mm thick, regardless of whether it's 2.5-inch or 1.8-inch.

Interface

This is the other crucial spec. Laptop hard drives come with IDE (parallel ATA)
and serial ATA (SATA) interfaces. Your laptop may also use a different connector as well. For example, IDE hard drives may use the standard IDE connector or a ZIF connector. Pay close attention to this, because these interfaces and connectors are not interchangeable.

RPM

RPM refers to the spindle speed of your hard drive. Standard for a laptop hard drive is 5,400 RPM. Choose a faster RPM—i.e. 7,200 RPM—for faster read/write speeds. Choose a slower RPM—i.e. 4,200 RPM—for less energy consumption. Given the other tech specs common in notebooks and netbooks, choosing a higher RPM doesn't usually realize a significant speed boost.

Capacity

This one is less crucial. Simply put, the greater the storage space, the higher the price tag. As of the time of this article, you can get a 250 GB 2.5-inch hard drive for as little as $40. The price goes up as you get into the 320 GB range and up.

Cache

The buffer, or cache, also affects speed. The higher the cache, the faster. Choose from 2 MB, 8 MB or 16 MB caches.

Resilience

One consideration that's unique to laptops is their ability to withstand shocks. That is, jostles, drops and physical trauma. For a laptop hard drive, you want it withstand at least 200 Gs of shock.

Power Consumption

The lower the power consumption, the better for your battery life. Choosing lower RPMs helps save on battery, but look for idle and read/write power ratings as well. A 7,200 RPM notebook hard drive that consumes 2 watts is passable.

Solid-state vs. Hard Disk Drive?

If you are value shopping, remove solid state hard drives completely from consideration. On a GB per dollar basis, solid state hard drives (or flash-based hard drives) are drastically more expensive than hard disk drives. Furthermore, many of the considerations above do not apply to solid state disks.

Conclusion

If you pay close attention to the form factor and interface, buying a laptop hard drive that's compatible with your machine should be no problem. But to remove all chances of incompatibility, refer to the manufacturer for recommendations for replacement or upgrade notebook hard drives.